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Targeted TB Testing & Interpreting Skin Test Results										Related Pages
										**Targeted Tuberculosis Testing and Interpreting Tuberculin Skin Test Results**
**Introduction**
The Centers for Disease Control and Prevention (CDC) and the U.S. Preventive Services Task Force (USPSTF) recommend testing populations that are at increased risk for tuberculosis (TB) infection. Once TB disease has been ruled out, those who would benefit from treatment of latent TB infection (LTBI) should be offered this option regardless of their age. Treatment adherence and completion are important for those who initiate treatment.
Health care providers should consider several criteria when classifying positive TST reactions.
**Table 1: Criteria for Classifying Positive TST Reactions**
Table 1: Criteria for Classifying Positive TST Reactions
Positive IGRA result or a TST reaction of 5 or more millimeters of induration is considered positive in
Positive IGRA result or a TST reaction of 10 or more millimeters of induration is considered positive inHIV-infected persons
Recent contacts of a TB case
Persons with fibrotic changes on chest radiograph consistent with old TB
Organ transplant recipients
Persons who are immunosuppressed for other reasons (e.g., taking the equivalent of >15 mg/day of prednisone for 1 month or longer, taking TNF-α antagonists)
Recent immigrants (< 5 years) from high-prevalence countries
Injection drug users
Residents and employees of high-risk congregate settings (e.g., correctional facilities, nursing homes, homeless shelters, hospitals, and other health care facilities)
Mycobacteriology laboratory personnel
Children under 5 years of age, or children and adolescents exposed to adults in high-risk categories**Positive IGRA result or a TST Reaction of 15 or more millimeters of induration is considered positive in**Persons with no known risk factors for TB** Although skin testing programs should be conducted only among high-risk groups, certain individuals may require TST for employment or school attendance. An approach independent of risk assessment is not recommended by CDC or the American Thoracic Society.**Persons at Risk for Developing TB Disease**
Generally, persons at high risk for developing TB disease fall into two categories: those who have an increased likelihood of exposure to persons with TB disease, and those with clinical conditions that increase the risk of progression from LTBI to TB disease.
Persons at risk for exposure to persons with TB disease include:
Close contacts of a person with infectious TB disease
Persons who have immigrated from areas of the world with high rates of TB
Residents and employees of high-risk congregate settings (e.g. correctional facilities, homeless shelters, health care facilities)Persons more likely to progress from LTBI to TB disease include:
Recent converters (those with an increase of 10 mm or more in size of TST reaction within a 2-year period)
HIV–infected persons
Young children who have a positive TST result
Those with a history of prior, untreated TB or fibrotic lesions on chest radiograph
Injection drug users
Those receiving TNF-α antagonists for treatment of rheumatoid arthritis or Crohn’s diseaseClinical conditions that increase the risk of progression from LTBI to TB disease:
HIV infection
Low body weight (> 10% below ideal)
Silicosis
Diabetes mellitus
Chronic renal failure or being on hemodialysis
Gastrectomy
Jejunoileal bypass
Solid organ transplant
Head and neck cancer**Special Considerations**
Questions often arise about the interpretation of TST results in persons with a history of Bacille Calmette-Gurin (BCG) vaccine, HIV infection, and recent contacts to an infectious TB case.
BCG vaccine is currently used in many parts of the world to protect infants and children from severe TB disease, especially TB meningitis. It does not confer lifelong immunity, and its significance in persons receiving the TST causes confusion in the medical and lay community.
History of BCG vaccine is NOT a contraindication for tuberculin skin testing
TST reactivity caused by BCG vaccine generally wanes with time
If more than 5 years have elapsed since administration of BCG vaccine, a positive TST reaction is most likely a result of *M. tuberculosis* infectionPersons who are HIV infected have a much greater risk for progression to TB disease if they have LTBI.
Individuals with HIV infection may be unable to mount an immune response to the TST and may have false-negative TST results
Usefulness of anergy testing in TST-negative persons who are HIV infected has not been demonstratedPersons with a positive TST result who are contacts of an individual with infectious TB should be treated regardless of age.
Some TST-negative persons should also be considered for treatment (i.e., young children, immunosuppressed)
Repeat TST in 8–10 weeks if initial test result is negative. A delayed-type hypersensitivity response to tuberculin is detected 2–8 weeks after infection**Testing Guidelines for Populations At Increased Risk for TB Infection**
NTCA/CDC. Guidelines for the Investigation of Contacts of Persons with Infectious TB. MMWR 2005;54(RR-15). https://www.cdc.gov/mmwr/preview/mmwrhtml/rr5415a1.htm
ATS/CDC. Targeted Tuberculin Testing andTreatment of Latent TB infection. MMWR 2000; 49 (No.RR-6) https://www.cdc.gov/mmwr/preview/mmwrhtml/rr4906a1.htm
CDC. Guidelines for Preventing Transmission of TB in Health-Care Settings. MMWR 2005;54(RR-17). https://www.cdc.gov/mmwr/preview/mmwrhtml/rr5417a1.htm
AAP. Recommendations for Preventive Pediatric Health Care, 2016. https://www.aap.org/en-us/Documents/periodicity_schedule.pdf**Additional Resources**
USPSTF. Latent Tuberculosis Infection: Screening Recommendation. http://www.uspreventiveservicestaskforce.org/Page/Document/UpdateSummaryDraft/latenttuberculosis-infection-screening
Targeted Tuberculosis (TB) Testing and Treatment of Latent TB Infection (slide set). https://www.cdc.gov/tb/publications/slidesets/LTBI/default.htm
ATS/CDC/IDSA. Clinical Practice Guidelines:Treatment of Drug-Susceptible Tuberculosis. Clin Infect Dis. (2016) http://cid.oxfordjournals.org/content/early/2016/07/20/cid.ciw376.full
TB Education and Training Resources website https://findtbresources.cdc.gov/
CDC Division of TB Elimination website https://www.cdc.gov/tb
CDC Division of TB Elimination Treatment FactSheets https://www.cdc.gov/tb/publications/factsheets/treatment.htm
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						Page last reviewed:  August 31, 2016					Content source: 	Division of Tuberculosis Elimination, National Center for HIV, Viral Hepatitis, STD, and TB Prevention, Centers for Disease Control and Prevention homeTuberculosisBasic TB Factsplus iconHow TB SpreadsLatent TB Infection and TB DiseaseSigns & SymptomsTB Risk FactorsExposure to TBTB PreventionVaccinesTB & HIV CoinfectionTB and DiabetesTB TermsPersonal StoriesTesting & Diagnosisplus iconWho Should be TestedTesting for TB InfectionTesting in BCG-Vaccinated PersonsTB Screening and Testing of Health Care PersonnelTesting During PregnancyDiagnosing latent TB infection and TB diseaseTreatmentplus iconDeciding When to Treat Latent TB InfectionTreatment Regimens for Latent TB Infection (LTBI)Treatment for TB DiseaseAdverse EventsTB Treatment of Persons Living with HIVTB Treatment and PregnancyTB Treatment for ChildrenFrequently Asked QuestionsDrug-Resistant TBResearchplus iconTB Epidemiologic Studies Consortiumplus iconResearch ProjectsPublicationsTB Trials Consortiumplus iconStudy DescriptionsBackgroundBehavioral & Social Science ResearchHealth Care Settingsplus iconTB Infection Control in Health Care SettingsResources for TB Screening and Testing of Health Care Personnelplus iconFrequently Asked QuestionsTB in Specific Populationsplus iconHealth DisparitiesAsian PersonsBlack or African American PersonsHispanic or Latino PersonsChildrenPregnancyCorrectional FacilitiesPeople Experiencing HomelessnessInternational TravelersLaboratory Informationplus iconDrug Susceptibility TestingFalse-Positive Investigation ToolkitInterim Laboratory Biosafety Guidance for XDR  tuberculosis strainsModel Performance Evaluation Program (MPEP)Rapid Molecular Testing to Detect Drug-Resistant TB in the USplus iconExecutive SummaryIntroductionBackground on Tests for Molecular Detection of DRGeneral Considerations and Principles for a Molecular DR Testing ServicePossible Scenarios and Scope of Testing for a Molecular DR Testing ServiceResearch NeedsGeneral Recommendations of the Expert PanelCommunication Plan for the ReportRecommendationsReferencesPanel Members and CDC ParticipantsAppendix 1Appendix 2Appendix 3The Uses of Nucleic Acid Amplification Tests for the Diagnosis of TBplus iconGeneral ConsiderationsGeneral Recommendations of the Expert PanelRecommendations to ACET, CDC, DTBEData & Statisticsplus iconTB Incidence in the United StatesReported TB in the US, 2022 Surveillance Reportplus iconNational DataReporting Area DataRisk FactorsDemographicsTB Treatment and Case OutcomesDrug-Resistant TBMolecular SurveillanceTuberculosis in the United States, 2022 (Slide Set)Archived Surveillance Reports and Slide Sets2021 State and City ReportArchived State and City ReportsProfessional Resources & Toolsplus iconTools for Healthcare ProvidersResources for TB Programsplus iconStrengthening Civil Surgeons’ Capacity to Improve LTBI Surveillance and Outcomes Among Status AdjustersNotice of Funding Opportunity (NOFO)Program EvaluationTB Centers of ExcellenceTB Elimination AllianceTB Genotypingplus iconConventional TB GenotypingWhole Genome SequencingTB GIMSAnalytic ToolsLatent Tuberculosis Infection ResourcesPublications & Productsplus iconPatient and Public MaterialsFact SheetsGuidelinesplus iconControl & EliminationDrug-Resistant TBInfection Control & PreventionLaboratory & GenotypingTB & HIVTB in Specific PopulationsTesting & DiagnosisTreatmentVaccines & ImmunizationsArchived TB GuidelinesGuides & Toolkitsplus iconAggregate ReportsCDC TB Surveillance TrainingCore CurriculumEffective TB Interviewing for Contact InvestigationEthnographic GuidesFalse-Positive Investigation ToolkitForging Partnerships to Eliminate TuberculosisGuide to Application of GenotypingLTBI: A Guide for Primary Health Care ProvidersMantoux Tuberculin Skin Testing ProductsReport of Verified Case of Tuberculosis (RVCT)Self-Study ModulesTB Contact Investigation Interviewing Skills CourseTB eDOT ToolkitUnderstanding the TB Cohort Review ProcessNewslettersplus iconTB Notes, No. 4, 2023TB Notes, No. 3, 2023TB Notes. No. 2, 2023TB Notes. No. 1, 2023TB Notes, No. 4, 2022TB Notes, No. 3, 2022TB Notes, No. 2, 2022TB Notes, No. 1, 2022TB Notes, No. 4, 2021TB Notes, No. 3, 2021TB Notes, No. 2, 2021TB Notes, No. 1, 2021Pamphlets, Brochures, Bookletsplus iconQuestions and AnswersPatient Education SeriesTuberculosis - Get the FactsTuberculosis - The Connection between TB and HIV12-Dose Regimen for Latent TB Infection-Patient Education BrochurePostersplus iconMantoux Tuberculin Skin Test Wall ChartWorld TB DayThink TBStop TBTake on TBReports & Articlesplus iconDTBE Authored Journal ArticlesTuberculosis Laboratory Aggregate ReportsSlide Setsplus iconIntroduction to TuberculosisEpidemiology of Tuberculosis Among Non-U.S.​–Born Persons in the United States, 1993–2016Self-Study Modules on Tuberculosis, 1-5 Slide SetsThe Tuberculosis (TB) in Correctional Settingsplus iconFacilitator GuideIntroduction to TB GenotypingEpidemiology of Tuberculosis in Correctional Facilities, United States, 1993-2017Prevention and Control of Tuberculosis in Correctional and Detention FacilitiesGuidelines for Preventing the Transmission of M. TB in Health care SettingsInvestigation of Contacts of Persons with Infectious TBEpidemiology of Pediatric Tuberculosis in the United StatesTargeted Tuberculosis Testing and Treatment of Latent Tuberculosis InfectionElectronic Tools & ResourcesWeb-Based Courses & Webinarsplus iconTB 101 for Health Care WorkersContent SyndicationInfographicsplus iconSocial Media GraphicsCustomizable Take on TB Infographic with InstructionsEventsWorld TB Dayplus iconU.S. TB ChampionsHistoryFeaturesplus iconTB Risk FactorsTreating Latent TB Infection with Short-Course RegimensWorld Tuberculosis (TB) Day 2021World Tuberculosis (TB) Day 2020Linksplus iconState TB Control OfficesAbout Usplus iconMission Statement and Activitiesplus iconDTBE Strategic PlanNational TB Program ObjectivesOrganization ChartAdvisory Groupsplus iconFederal TB Task Force To receive email updates about this page, enter your email address: Email Address			What's this?				Submit


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